Forge 47.2.17
Create 0.5.1.f
Destroy 0.2

When attempting to use Pick Block on a placed Extrusion Die, it does not register as the same one existing in a player's inventory, causing it to not be selected in Survival Mode and creating a duplicate in the hotbar in Creative Mode.

Fixed in 1.0.

I'm unable to replicate this. Do you have any other mods installed? If you run /data get entity @s when you have both 'different' Extrusion Dies in your inventory what do you get?

Here, I have attached a gif.
The only other mod in this instance is Just Enough Items
Nothing in /data indicates a difference in the items in my inventory

That is really weird. I'm still unable to replicate this, so I'll wait and see if anybody else experiences it. I have no clue what could be causing it because the Extrusion Die doesn't do anything weird with its item.

can confirm as well, but the pickblocked items are indeed the same, i can stack them up